ITMI20112033A1 - MACHINE FOR BLOWING OR IRONING OF BOTTLES IN POLYMERIC MATERIAL - Google Patents

Description

BLOWING OR IRONING MACHINE -

BLOWING OF BOTTLES IN POLYMERIC MATERIAL

Description

The present invention relates to a machine for blowing or stretch-blowing of preforms made of polymeric material suitable for transforming said preforms into bottles or containers.

Obtaining bottles or containers by blowing special preforms suitably heated inside a mold of the desired shape is a technique widely used in the packaging sector, in particular for the manufacture of bottles or containers.

There are essentially two different techniques, simple blowing and stretch-blowing, which involves pneumatic blowing and the simultaneous mechanical stretching of the preform into the mold. In both cases the preforms must reach the blowing or stretch-blowing machine in a thermal condition that corresponds to the softening point of the material, so that they can be plastically deformed inside the molds.

The production of these bottles often requires a rather high production speed and hourly rate due to the need to reduce to the minimum possible the forming costs of the single bottle or container, as they would heavily affect the final cost of the product.

Many efforts are therefore aimed at automating and speeding up the process.

Machines are known for blowing or stretch-blowing of preforms comprising a plurality of openable molds comprising two half-molds hinged at one end and operated by suitably arranged and sized levers to allow opening and closing of the same in a synchronized manner with predetermined loading phases. of the preforms and discharge of the already formed bottle. These levers are generally operated by means of a coupling with shaped cams, this coupling being able to provide an alternating motion with a course defined by the shape of the cam itself.

More in detail, such a coupling includes a suitably shaped profile so-called `` cam '' and a sliding element, so-called `` ceding '', forced to slide along this profile and able to provide a mechanical user with a movement that depends on the shape of the profile.

Often, to obtain a high rate, a plurality of molds are arranged radially around a central axis of rotation on a rotating blow molding machine, in which the means for opening and closing the molds are synchronized with the movement of other devices which cooperate in the operation of the machine, for example a device for moving the preforms at the inlet and the bottles at the outlet, or a blowing device for moving different components of the molds.

In this way some work steps on each subsequent bottle according to the rotation of the machine are carried out in the shadow of other work steps on the previous bottle.

Generally, the aforesaid mechanical devices are operated individually by separate individual cams, suitably shaped according to the sequence or duration of the movements. In particular, the various devices of a mold have their respective followers protruding and oriented so that in a predetermined portion of the rotation of the machine they are channeled into respective guides or cams, shaped in a suitable way to impart predetermined movements to the follower, which carries these input movements to the various devices in a predetermined way.

In particular, in a known rotary machine having a plurality of molds, each mold comprises two half-molds hinged around a hinge axis parallel to the rotation axis of the machine, which can be closed or opened in a synchronized manner by means of an actuation device operated by a cam coupling.

In this known machine, the half-molds have an end opening, arranged in a direction parallel to the hinge axis, corresponding to a bottom portion of the bottle to be obtained. This opening is adapted to be alternately closed and opened by a bottom adapted to be moved in a direction substantially perpendicular to the bottom of the bottle. The bottom supports a portion of the mold adapted to allow the bottom of the bottle to be formed, which has projections and recesses extending in a direction substantially perpendicular to the bottom.

In the aforesaid known machine the bottom is moved by means of a mechanism that receives the motion from a respective follower that can be associated with a separate cam from the one that activates the opening and closing of the mold.

This known type of mold has the disadvantage that during the blowing of the preform the pressure of the fluid, generally air, inside the preform and therefore of the mold, exerts an opening force on it, which tends to open it and to misalign the edges contour of the half-molds with the consequence of producing an imperfect bottle in which the separation line between the half-molds remains clearly visible.

The known technique, to obviate this problem, provides for the use of a latch able to be inserted slidingly in peripheral passages obtained at one end of the molds opposite the hinge axis, which, when the mold is closed, are aligned with each other, allowing the latch to be inserted into the passages and holding the mold in a closed configuration during blowing. This bolt must therefore be inserted into the passages before blowing to keep the half-molds closed and removed after blowing to allow subsequent opening. This bolt is activated automatically by means of a respective follower which engages on a separate cam from the one which activates the opening and closing of the gripper.

While solving the problem of keeping the half-molds closed, the presence of the latch entails the further disadvantage of slowing down the production chain as it can only be inserted when the mold is completely closed and therefore it is not possible to insert it in the shadow of the movement of opening and closing of the mold itself.

Furthermore, the presence of the bolt entails the disadvantage of having to use an additional cam and a corresponding expenditure of mechanical energy.

Moreover, such a known machine entails the disadvantage of requiring very high precision in sizing and assembly of the distinct cams, in arranging them in the correct relative position between them to provide the correct mechanical synchronization of the various mechanical devices operated in the machine and in particular of the gripper and bottom, as well as the insertion of the latch. If the different cams are not mounted with very high positioning accuracy, there could be forcing between the various mechanical parts which would lead to rapid wear of the mechanical couplings. Also, due to high operating speeds, in extreme cases mechanical interference or shocks may occur in movements resulting in damage to the machine.

For these reasons, such a known machine prevents a maximum production rate from being exceeded.

The problem addressed by the present invention is to provide a machine for blowing or stretch-blowing of plastic bottles which allows the above-mentioned disadvantages to be overcome.

This problem is solved by a machine as outlined in the attached claims, the definitions of which form an integral part of the present description.

Further characteristics and advantages of the present invention will become clearer from the description of some embodiment examples, given below by way of non-limiting example, with reference to the following figures:

Figure 1 represents a schematic plan view of a blowing or stretch-blowing machine according to the invention, having a plurality of mold units;

Figures 2 and 3 show a perspective view of a mold unit of a machine according to the invention, respectively in the configuration of closed mold and open mold;

Figures 4 and 5 show a plan view of the mold unit of Figure 2 respectively in the configuration of closed mold and open mold;

Figures 6 and 7 show a side view of the mold unit of Figure 2 respectively in the configuration of closed mold and open mold.

With reference to the figures, the number 1 indicates a blowing or stretch-blowing machine according to the invention, of the rotary type and having a plurality of molds 20 arranged radially with respect to a substantially vertical axis of rotation 2 of the machine 1.

Each mold unit 10, rotating around the rotation axis 2 of the machine, is brought cyclically to a station for loading a preform and / or unloading a bottle obtained from the preform. Between the loading of the preform and the unloading of the bottle, blowing or stretch-blowing is performed.

According to a general embodiment, each mold unit 10 comprises a mold 20 having a first mold half 21 and a second mold half 22 hinged around a hinge axis 23, for example parallel to the rotation axis 2 of the machine. The hinge axis is arranged at a lateral end of the half-molds 21 and 22 facing towards axis 2 of the machine.

The first mold half 21 and the second mold half 22 can therefore rotate around the hinge axis 23 between a closed mold configuration (Fig .: 2, 4 and 6) in which the mold halves 21 and 22 are in contact along respective edges 24 mold and an open mold configuration (Fig .: 3, 5 and 7).

The half-molds 21 and 22, therefore, can be opened / closed like two shells of a bivalve shell.

According to one embodiment, the half-molds 21 and 22 are able to close when approaching a closing plane X-X passing through the hinge axis 23, in particular the closing plane X-X also passing through axis 2 of the machine. In this way each mold 20 can be opened towards the outside of the machine 1.

The mold unit 10 comprises a bottom 52 suitable for cooperating with the half-molds 21 and 22, and means 50 for moving the bottom, to cyclically form a closed cavity 24 suitable for receiving a preheated preform and allowing expansion by blowing or stretch-blowing of the preform inside cavity 24 to obtain a bottle or container.

Advantageously, the half-molds 21 and 22 and the bottom 52 are operated by means of opening / closing 12 of the half-molds 21 and 22 and means for moving the bottom 50, in a synchronized way starting from a single motion input 36 comprising a single coupling to cam.

Advantageously, the half-molds 21 and 22 rotate around the hinge axis 23 simultaneously with a translation of said hinge axis 23 along the X-X plane in a direction substantially perpendicular to the same hinge axis.

According to one embodiment, the half-molds 21 and 22 comprise a respective shaped portion which repeats in negative the external shape of the bottle to be obtained from the preform and which delimits the space inside which the preform is made to expand, in which this shaped portion is It can be separated from the half-molds 21 and 22 and interchangeable, so as to allow the forming of bottles having different shapes and sizes. In this way it is sufficient to replace the shaped portions to start the production of different bottles.

In a possible embodiment, the aforementioned closing / opening means of the mold 20 comprise a crankshaft having a main axis of rotation 26, integral with the blowing machine 1, arranged substantially parallel to the hinge axis 23, and an eccentric axis 27, parallel to the main axis 26 and spaced from the eccentric axis 27 by a predetermined arm value B.

According to one embodiment, the main axis of rotation 26 coincides with the axis of two cylindrical end sections 28 and 29 of the crankshaft 25, the so-called â € œbench journalsâ €, while the eccentric axis 27 coincides with a cylindrical central section 30, the so-called â € œ crank pin "interposed between the end sections 28 and 29. The crank pin 30 is rigidly connected to the main journals 28 and 29 by means of arms 31 and 32.

According to an embodiment, the closing / opening means comprise at least one connecting rod 33 having a first end 34 rotatably connected around said eccentric axis 27 and a second end 35 rotatably connected around said hinge axis 23.

In a possible embodiment four connecting rods 33 are provided having a first end 34 rotatably connected around said eccentric axis 27 and a second end 35 rotatably connected around said hinge axis 23.

In one embodiment, the closing / opening means of the mold 20 comprise at least a first crank 40 having a first end rotatably connected to a first fixed axis 37 integral with the machine 1 and a second end rotatably connected around a first axis 43 of the first half-mold 21 on the same side of the X-X plane with respect to the first fixed axis 37.

In one embodiment, the closing / opening means of the mold 20 comprise at least a second crank 41 having a first end rotatably connected to a second fixed axis 38 integral with the machine 1 and a second end rotatably connected around a second axis 44 of the second half-mold 22 on the same side of the X-X plane with respect to the second fixed axis 38.

According to one embodiment, the opening closing means comprise two first cranks 40 substantially equal and two second cranks 41 substantially equal.

According to a possible embodiment, the fixed axes 37 and 38 and / or the first lateral axis 43 and the second lateral axis 44 are substantially parallel to each other and substantially parallel to the hinge axis 23.

According to an embodiment, the first lateral axis 43 and the second lateral axis 44 are spaced on opposite sides with respect to the closing plane X-X.

In one embodiment, the at least one first crank 40 and / or the at least one second crank 41 are arranged on a plane substantially orthogonal to the hinge axis 23.

In a possible embodiment, the at least one first crank 40 and / or the at least one second crank 41 are arranged oblique with respect to the closing plane X-X.

According to one embodiment, the fixed axes 37 and 38 are distant from the closing plane X-X by a value greater than the distance of the first lateral axis 43 and of the second lateral axis 44 from the closing plane X-X.

According to an embodiment, the first fixed axis 37 and the first lateral axis 43 are arranged specularly to the second fixed axis 38 and to the second lateral axis 44 with respect to the closing plane X-X.

The rotation of the crankshaft 25 around its main axis 26 forces the eccentric axis 27 to rotate around the main axis 26 according to a radius equal to B. This rotation drags the at least one connecting rod 33 so to impart to the hinge axis 23 an alternative translation motion along the X-X closing plane between a closing position of the mold in which the eccentric axis 27 is aligned with the main axis 26 along the closing plane X-X and on the opposite side to the hinge axis 23 (Fig .: 4), and an opening position of the mold in which the eccentric axis 27 is aligned with the main axis 26 along the X-X closing plane on the same side as the hinge axis 23 (Fig .: 5).

At least one connecting rod 33 cooperates with at least one first crank 40 and / or at least one second crank 41, forcing the two half-molds 21 and 22 to rotate with respect to the hinge axis 23 simultaneously with the translation of the Hinge axis 23 thus closing or opening the mold 20.

This embodiment of the opening / closing means of the mold 20 has the advantage that when the mold 20 is closed, the two half-molds 21 and 22 are pressed together by the combined effect of a compression force exerted by the at least a first crank 40 and by at least a second crank 41 and a traction force exerted by the at least one connecting rod 33, thus preventing any further opening movement of the half-molds 21 and 22.

In fact, when the mold is closed, the at least one connecting rod 33 applies to the hinge axis 23 a force oriented from the hinge axis 23 towards the main axis 26 of the crankshaft 25 and at the same time each first crank 40 and second crank 41 apply, to the respective lateral axis 43 and 44, a respective force arranged along the joining between the fixed axis 37 and 38 and the lateral axis 43 and 44 and facing the closing plane X-X. These forces have a component normal to the X-X locking plane and directed towards the X-X locking plane. In this way the pressure that is exerted between the half-molds 21 and 22 during blowing is compensated by these normal components in synergy with the geometric non-compliance of the half-molds 21 and 22.

In other words, these opening / closing means allow the self-locking of the half-molds when they are in the closed position to counteract the pressure that is exerted inside the cavity during the blowing into the preform to expand it and obtain the bottle.

This advantage makes it possible to prevent the need for the presence of clamping means suitable for holding the half-molds 21 and 22 closed during blowing. Therefore, it makes it possible to avoid the use of a latch able to hold the closed half-molds.

A positive consequence of this advantage is the complete elimination of the waiting time for inserting and removing the latch respectively before and after blowing, with a reduction in production times and an increase in production rates.

According to one embodiment, the mold unit 10 is adapted to receive the motion by means of a torque applied to the main axis 26, for example by means of a coupling with toothed wheels. For example, at one end of the crankshaft 25 there is a toothed wheel 36 coaxial with the main axis 26.

According to an embodiment, the mold unit 10 comprises motion input means adapted to take motion from a coupling with a conjugate profile and transmit it to the crankshaft 25 by applying a torque around the main axis 26.

In accordance with an embodiment, these motion input means comprise a rotation axis 70, a toothed sector 71 able to rotate around the rotation axis 70 and able to engage on the toothed wheel 36, a crank 72 integral with the toothed sector 71, having axis of rotation coincident with axis 70, a crank end having a protruding or yielding pin 73, able to engage slidingly on a shaped profile, or cam, shaped so as to impart to the sector tooth 71 a rotation of a suitable value to make the toothed wheel 36 rotate by a predetermined angle so as to complete a whole cycle of opening and closing the mold 20.

In one embodiment, this predetermined angle for bringing the mold 20 from the open configuration to the closed one or vice versa is substantially equal to 180 °.

In one embodiment, the half-molds 21 and 22 comprise a bottom opening 51 in correspondence with a bottom portion of the bottle to be obtained, said opening being able to be closed alternately by the aforementioned bottom 52, so that said opening 51 is closed from said bottom 52 when the half-molds 21 and 22 are closed, and is open when the half-molds 21 and 22 are open.

In one embodiment, the opening 51 is obtained in a direction parallel to the hinge axis 23 and arranged in a lower area of the half-molds 21 and 22.

According to one embodiment, the mold unit 10 comprises means 50 for automatic movement of the bottom 52, in particular adapted to translate the bottom in a direction parallel to the hinge axis 23 between a lower opening position and an upper position of closure.

In one embodiment, the mold unit 10 comprises a hinge pin 54 having an axis coinciding with the hinge axis 23, said hinge pin extending beyond the half-molds 21 and 22 from the side of the bottom opening 51 and a shelf 53 slidingly connected to the hinge pin 54 so as to be able to translate along the hinge axis 23, said shelf 53 integrally supporting the bottom 52.

According to a possible embodiment, the shelf 53 is connected to the hinge pin 54 by means of a sliding guide 55 parallel to the hinge axis 23 and integral with the hinge pin 54, and a slide 56 integral with the shelf 53 and sliding on the guide 55.

According to an embodiment, the means 50 for moving the bottom 52 comprise at least a pair of connecting rods 58 and 59 mounted in series and rotatably connected to each other around a common axis of rotation 59 so that a first end of a connecting rod 57 is connected to a first end of the other connecting rod 58. These connecting rods 57 and 58 are mounted interposed between the bracket 53 and a support arm 62 fixed to the hinge pin 54 on the opposite side to the bracket 53 with respect to the connecting rods 57 and 58 , and have a second end rotatably connected respectively to the bracket 53 and to the support arm 62. Said movement means also comprise a control arm 63 having a first end rotatably connected to the connecting rods 57 and 58 around the common axis of rotation 59, and a second end rotatably connected to a fixed axis 64 integral with the machine 1. The arm 63 is arranged so as to be able to rotate on the plate. closing number X-X around the fixed axis 64, which belongs to a support 65 integral with the machine 1.

The operation of the means 50 for moving the bottom 52 is described below.

The translation motion of the hinge axis 23 along the closing plane X-X brings the hinge pin 54 into reciprocating translation motion between an opening position of the half-molds and a closing position. When the hinge pin 54 is in the mold opening position (fig 7), therefore in the position furthest away from the main axis 26 of the crankshaft 25, this hinge pin is in the position closest to the Fixed axis 64 of arm 63. In this configuration the second ends of the connecting rods 57 and 58 are constrained to rotate in approach around the common axis 59 causing the bracket 53 to approach the support arm 62, and therefore the Removal of the bottom 52 from the opening 51.

When, on the other hand, the hinge pin 54 is in the closing position of the molds (Fig 6), the hinge pin 54 is in the position closest to the main axis 26 of the crankshaft 25 and therefore in the position furthest from axis 64. In this configuration the second ends of the connecting rods 57 and 58 are constrained to rotate away, causing the bracket to move away from the support arm 62, and therefore the bottom 52 to approach the ™ opening 51.

According to one embodiment, the mold unit 10 comprises guide means adapted to constrain the motion of the hinge axis 23 to the translation only in a direction orthogonal to the axis 23 itself and along the X-X closing plane.

In one embodiment, these means comprise a guide 66 substantially orthogonal to the hinge axis 23 and belonging to the closing plane X-X, integral with the machine 1, and a slide 67 integral with the hinge axis 23 and sliding on said guide 66 .

According to one embodiment, the slide 67 is fixed to the support arm 62.

It is evident that only some particular embodiments of the present invention have been described, to which the expert in the art will be able to make all the modifications necessary for its adaptation to particular applications, without departing from the scope of protection of the present invention.

Claims (12)

CLAIMS L. Machine (1) for blowing or stretch-blowing of bottles or containers in polymeric material having a plurality of mold units (10), each mold unit (10) having a first side mold half (21) and a second side mold half (22), hinged around a hinge pin (54) having a hinge axis (23), and a bottom (52) cooperating with said first mold half (21) and second mold half (22) to cyclically form a closed cavity (24) suitable for receiving a preheated preform and allowing the expansion by blowing or stretch-blowing of the preform inside the cavity (24) to obtain a bottle or container, said mold unit (10) being designed to cyclically assume a closed mold configuration and a configuration of a mold open towards and away from a closing plane X-X passing through said hinge axis (23), said mold unit (10) comprising opening / closing means (12) of the half-molds (21, 22) and means of mov entation (50) of the caseback, characterized by the fact that: - said half-molds (21, 22) and said bottom (52) are operated, by means of said opening / closing means (12) of the half-molds (21, 22) and means for moving the bottom (50), in a synchronized way starting from a single motion input (36) comprising a single cam coupling; - said half-molds (21, 22) rotate around said hinge axis (23) simultaneously with a translation of said hinge axis (23) along the X-X plane in a direction substantially perpendicular to the same hinge axis. 2. Machine according to claim 1, wherein said opening / closing means (12) comprise at least one connecting rod (33) adapted to translate said hinge axis (23) along the X-X plane, alternatively between an advanced position and a position and in which said half-molds (21 and 22) are movably connected to a fixed constraint (37, 38) by means of connection in such a way that said half-molds (21 and 22) are open in said forward position and closed in said position backward. 3. Machine according to claim 2 wherein said connecting means comprise at least one crank (40, 41). 4. Machine according to at least one of the preceding claims, in which said opening / closing means (12) are adapted to automatically lock and press said half-molds (21, 22) against each other when the mold unit (10) is ̈ in the closed mold configuration, applying closing forces converging in a substantially tangential direction with respect to said hinge axis (23). 5. Machine according to a previous claim, wherein said closing / opening means (12) comprise: - a crankshaft (25) having at least one main portion (28, 29) having an axis of rotation (26) substantially parallel to said hinge axis (23), and an eccentric portion (30) with axis (27) parallel to said main axis of rotation (26) and spaced apart from the eccentric axis (27) by a predetermined arm value B; - at least one connecting rod (33) having a first end (34) rotatably connected to said eccentric portion (30), and a second end (35) rotatably connected around said hinge axis (23); - at least a first crank (40) having a first end rotatably connected to a first fixed axis (37) integral with the machine (1) and a second end rotatably connected around a first lateral axis (43) of said first mold half (21) on the same side of the closing plane X-X with respect to said first fixed axis (37); - at least a second crank (41) having a first end rotatably connected to a second fixed axis (38) integral with the machine (1) and a second end rotatably connected around a second lateral axis (44) of the second mold half (22) from same part of the X-X closing plane with respect to the second fixed axis (38); in which, in said closed mold configuration, said eccentric axis (27) is aligned with said main axis (26) along the X-X closing plane and on the opposite side to the hinge axis (23) with respect to the axis main axis (26), and in said open mold configuration the eccentric axis (27) is aligned with the main axis (26) along the X-X closing plane and interposed between said main axis (26) and said axis hinge (23). 6. Machine according to a previous claim, in which said fixed axes (37, 38) and said first lateral axis (43) and second lateral axis (44) are substantially parallel to each other and substantially parallel to the hinge axis (23 ). 7. Machine according to a preceding claim, in which said at least one first crank (40) and / or said at least one second crank (41) are arranged oblique with respect to the closing plane X-X and / or in which said first and second fixed axes ( 37, 38) are spaced from the closing plane X-X by a greater value than the distance of said first and second lateral axes (43, 44) from the closing plane X-X, and / or in which said first and second fixed axes (37, 38) are interposed between said lateral axes (43, 44) and said main axis (26) 8. Machine, according to a previous claim, in which said first fixed axis (37) and said first lateral axis (43) are arranged specularly to the second fixed axis (38) and to the second lateral axis (44) with respect to said X-X closing plane . 9. Machine according to a preceding claim, comprising guide means suitable for allowing the hinge axis (23) to be translated only in a direction orthogonal to the hinge axis (23) and along the X-X closing plane. 10. Machine according to a previous claim, in which said guide means comprise a guide (66) substantially orthogonal to the hinge axis (23) integral with the machine (1) and belonging to the closing plane X-X, and a slide (67 ) integral with the hinge axis (23) and sliding on this guide (66). 11. Machine, according to a preceding claim, in which said bottom moving means (50) comprise: - means for sliding engagement (55, 56) of said bottom (52) to said hinge pin (54) which allow a movement towards or away from said bottom (52) to / from said half-molds (21, 22); - at least one pair of connecting rods (57, 58) mounted in series and rotatably connected to each other around a common axis of rotation (59) so that a first end of a connecting rod (57) is connected to a first end of the another connecting rod (58) and a second end is connected respectively to said bottom (52) and to a support arm (62) integrally fixed transversely to said hinge pin (54), said pair of connecting rods (57, 58) being interposed between said base (54) and said support arm (62); - a control arm (63) having a first end rotatably connected to said first ends of said connecting rods around the common axis (59) and a second end rotatably connected to a fixed axis (64) integral with the machine (1), said approach or removal movement of said bottom (52) being directly driven by said translation movement of said hinge pin (54). Machine according to a preceding claim, wherein each said mold unit (10) comprises motion input means (16) comprising: - a toothed sector (71) having a fixed rotation axis (70) integral with the machine (1) adapted to mesh with a toothed wheel (36) integral and coaxial with a main portion (29) of the crankshaft ( 25); - a crank (72) integral with the toothed sector (71), having a first end rigidly connected to said toothed sector (71) along said axis (70) of said sector, and a second end having a protruding pin (73) adapted to slidingly engaging along a shaped guide cam.